How might PWK designed a wallhorn to go deeper than LS?

[LousyTourist]

Dennis, you mean their subwoofer?

[djk]

Not that one, the B-DEAP32. The USPTO has the plans on-line in the patents applied for section.

It is placed in the corner as in fig.5C that D-MAN posted. The 150hz mid horn shown with the Jubilee is about 30" wide, and only 24" deep. The B&C driver Klipsch used to use has a version with a 1-1/2" throat with better dispersion in the top octave than the 2" model. The current Klipsch version is from a different OEM, and may be even better. It is also available in a 1-1/2" throat version, and either are very affordable.

Here is the Klipsch

http://forums.klipsch.com/forums/storage/3/776103/K402-K69A-TerminalBlock.jpg

Here is a different driver from the same OEM (but not the same model)

http://www.martinsoundpro.com/upload/item/1086,1087.jpg

This OEM makes various different drivers for JBL, Peavey, Eminence, and many others.

These are some very similar mids I used to have twent-six of back about 20 years ago

http://www.gravitymusicgear.com/pictures/mids_062404.JPG

They use an OEM version of the EVM12L

I use an EV DH1A on top. Klipsch used to use this driver before they went to B&C, and before their current OEM. I use the EV HP640, a very close pattern match for dispersion, and it is mechanically time-aligned with the mid.

http://www.electrovoice.com/products/296.html

This horn has vanes in the throat like the original Klipsch K5 horn, and was designed by Don Keele, who mentions PWK in the design article about his horns, and worked for Klipsch between his tenure at EV and later JBL.

Bass horns have to be quite large to work properly. I use push-pull pairs below 100hz to get better performance for smaller size. These have less distortion than most horns, and are easy to build.

http://www.audiolabo.fr/images/stories/audio_labo/montage.jpg

[jwc]

Someone please tell me how to search the patent you are speaking of.

Thanks.

jc

[freddyi]

hey JC - outta room too but curious about your drawing. (has it been simed?)

Freddy

[jwc]

I don't understand the question.

[freddyi]

hey DJK - how far up do you think BDEAP could operate smoothly? how much plywood does it take ot build one?

hey JC- just wondering if you have simulated your 18" horn with David McBean's Horn Response or some other software? (DJK suggested my trying PV18 lowrider in FH1 but have to open its throat-?)Freddy

[DrWho]

Related question?

What do you folk think of the idea of flush mounting a Belle or La Scala -- the way some studios flush mount their speakers, and Jeff Cooper recommends? That should increase deep bass a bit, but how? I assume that concerns about treble and mids spilling sideways and being reflected could be handled by putting absorptive materials to either side of the mid/tweet top of either of these speakers, which may have less side radiation than some studio flush mounted speakers, anyway.

Flushmounting, when properly done, is always a great idea. Attached is a graph indicating the anticipated gains from a speaker's ground-plane measurement.

I wouldn't worry too much about the MF/HF energy being affected by the flush-mounting. If anything you would be getting rid of the diffraction along the corners of the speaker. Proper flushmounting practice involves decoupling the speaker from the wall it's flushmounted in and providing the necessary damping and frame over the holes to keep cabinet vibrations behind the wall.

[djk]

http://www.freepatentsonline.com/20040238268.html

Click on 'View PDF Images '

wait a minute, and click on 'refresh'.

Or go to the USPTO and click on 'images' (requires a TIFF viewer)

http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220040238268%22.PGNR.&OS=DN/20040238268&RS=DN/20040238268

[djk]

"hey DJK - how far up do you think BDEAP could operate smoothly?"

Maybe 200hz for a crossover point. Gets kind of funky above 180hz. Most people would probably do 150hz or so.

" how much plywood does it take ot build one? "

Maybe 5~6 sheets of 5X5 for a pair, probably 3 for 1 box.

[jwc]

freddyi

I see what you are saying. I haven't used any software yet. I have tried some before but they tend to confuse me.

What I typically have done recently is calculate the throat based on a drivers T/S parameters such as Vt = (0.8)Fs x Qes x Vas (in cu in). I believe this is the way Edgar did this for the Show Horn.

The ideal volume of the back chamber was calculated but off the top of my head...I have forgotten where I got that.

Anyway, was messin around with the Eminence Magnum HO. Basically a rear firing folded horn like the La Scala. Now is wasn't a copy. The initial flares/ramps are different. The depth of the flares were I think 4" instead of 3". The width of the whole cabinet was less than a Bell and the depth right at 24 3/4". I belive it was a 55Hz horn, 1/8 space, Full exponential. The length of the horn was I think 85-89cm. The throat was 105 sq in. One driver. The bass bin was slightly shorter that the scala bass bin.

I thought it would be "nice looking" as It seems very hard to me to create something that stays appealing to the eyes. If figured it would go much lower than a scala as it is a 70Hz horn. NOw it is a "short horn with a big throat". Again, I believe Dana mentioned a problem with that concept. Forgot what it was.

If someone want to run the numbers mentioned above...shoot. I'm at work and don't have all the stuff in front of me.

jc

[D-MAN]

Ah, the "foreshortened horn" problem. If the path length of the horn is too short, it will produce a "peaky" frequency response. Famously illustrated by Olson in his seminal work "Acoustic Engineering". However, Olson left out one very important consideration, he did not show the results of a foreshortened horn WITH a reactance-annulled driver. He simply changed the mouth sizes, which automatically shortened the horns, too. Salmon, Plach, Klipsch, Edgar all agree that the horn can safely be "foreshortened" IF one also pays attention to the back chamber sizing with regard to frequency.

The detrimental response from a foreshortened horn can be alleviated somewhat by fully reactance-annulling the back chamber. The drawback is that the roll off below the horn Fc will be exagerated, and may not be effectively EQ'd.

A fully-reactance annulled driver is less susceptable to variations in acoustic resistance (from a fore-shortened horn) than a non-fully annulled one.

Another consideration is that PWK stated in the Gillum patent that a horn mouth could be as small as 1/12th of a wavelength (with a reactance-annulled driver). That also means that a horn pathlength is also reduced by the same ratio (as determined by the flare rate), and consider the result the minimum horn path length that you can safely use.

DM